Method references with a parameter

问题:

In Java 8, with the following class

 class Person {

    private boolean born;

    Person() {
    }

    public void setBornTrue() {
        born = true;
    }

    public void setBorn(boolean state) {
        born = state;
    }

  }

it is possible to call the setBornTrue method via a method reference:

    ArrayList<Person> people = new ArrayList<>();
    people.add(new Person());

    people.forEach(Person::setBornTrue);

but how would I use the forEach method and use the setBorn using a method reference? Trying:

    people.forEach(Person::setBorn);

results in an error, "Cannot resolve method setBorn".

In addition, how would I pass in the value of True?

回答1:

With lambda:

people.forEach((p) -> p.setBorn(true));

Found no other ways only using the java 8 API.

---

With this custom function:

public static <T, U> Consumer<T> bind2(BiConsumer<? super T, U> c, U arg2) {
    return (arg1) -> c.accept(arg1, arg2);
}

You can do:

people.forEach(bind2(Person::setBorn, true));

If this kind of utility methods is available in the java API or in a library, please let us know.